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Our company maintains air emissions per megawatt-hour at or below industry averages. This is achieved through the use of non-emitting nuclear power and renewable energy in our generation mix, emissions control technology, improved power plant efficiency and a more-diverse fuel mix which includes nuclear, gas/oil, coal and renewables. In addition, we have an aggressive demand-side management program that works to improve energy efficiency and reduce per capita demand.
The air emission charts below show our air emissions of primary pollutants from power plant electricity generation over the last five years. These charts show a generally continuing longer term downward trend in the emissions intensity for the priority pollutants. Carbon dioxide emissions are discussed in the Climate Change section of this report.
APS plants comply with existing Clean Air Act (CAA) regulations. However, as we plan for the future, we recognize the need to continue to reduce air emissions in our operations, both in new generating facilities and in improving current facilities. Air emissions are a major consideration in our resources planning process for new generating facilities. In addition, we are taking significant steps to reduce air emissions in our existing facilities, as described below.
APS initiated discussions with a variety of stakeholders, including the US EPA and the Arizona Department of Environmental Quality (ADEQ), regarding voluntary sulfur dioxide (SO2) and nitrogen oxide (NOx) emission reductions at the Cholla Power Plant, resulted in an agreement in 2005 to implement several pollution control enhancements at the Cholla plant. The following is the status of the projects:
- Unit 1: a new fabric filter (bag-house), low-NOx burners (LNBs) and carbon monoxide (CO) continuous emissions monitors (CEMS) have been installed. Changes to the S02 scrubber were completed. All equipment is now operational.
- Unit 2: LNBs and CO CEMS have been installed, and final tuning of instruments and systems is progressing.
- Unit 3: we will replace the existing hot-side electrostatic precipitators (ESPs) with a new fabric filter (bag-house), install new LNBs, CO CEMS, and a new SO2scrubber and controls in 2009.
- Unit 4: we are replacing the existing hot-side ESPs with a new fabric filter (bag-house), installing new LNBs, CO CEMS and a new SO2 scrubber, and the unit will be operational with this new equipment in May 2008.
This collaborative approach for voluntarily achieving more emission reductions sooner – and at lower costs – assures Cholla’s economic viability and benefits APS shareholders, customers, regulators and most importantly, the environment.
In 2003, APS, various Environmental Groups, Navajo EPA, U.S.EPA, and the National Park Service agreed on a proposal to test potential reductions in SO2 emissions at the Four Corners plant, utilizing an 18-month-long test program. The test program involved certain phased operational changes and scrubber chemical process changes to increase the SO2 control level from 72 percent to 85 percent, without triggering operational problems. APS initiated the test program in early 2004.
The test program was completed during summer 2005. APS determined that the plant was able to meet and exceed the goal of 85 percent SO2 removal by achieving an SO2 removal rate of 88 percent. At that elevated control level, the plant was able to cut its annual SO2 emissions by more than 55 percent, compared to the pre-test level. APS worked with the various groups involved, including the regulatory agencies, to incorporate the higher SO2 control level as an enforceable emission limit for the plant. The figure below shows historic and projected future Four Cornersemissions, and illustrates a dramatic drop in SO2 in 2005 from the test program.
APS has submitted a BART analysis for NOx and PM emissions to EPA, Region 9. The analysis indicates that LNB is BART for Units 1-2 and LNB/OFA is BART for Units 3-4-5, and that existing PM controls constitute BART.
Employee Travel Reduction is an important part of our EHS programs, particularly in the Phoenix area – a U.S. Environmental Protection Agency (EPA) non-attainment area for particulate matter and eight-hour ozone standard. We encourage employee travel reduction activity and offer subsidies to further persuade our employees to use alternative means of transportation. Our subsidies cover a portion of the costs for vanpooling, bus fares and carpool parking. We accommodate compressed work weeks, telecommuting and videoconferencing. We also offer assistance to employees in finding carpool partners, and in setting up carpools. The Travel Reduction Program also has a reward program for employees participating in travel reduction on High Pollution Advisory days.
 APS maintains a fleet of 167 vans that operate daily for employees commuting between Palo Verde Nuclear Generating Station (PVNGS) and the Phoenix area. APS began operating this program in 1994 and almost 62 percent of the permanent APS employees at PVNGS participate. This program has significantly contributed to the site achieving a single occupant vehicle (SOV) rate well below the 60-percent target. The fleet approaches five million commuting miles annually. The commuting miles eliminated with this outstanding program is more than 32.7 million annually, resulting in a pollution savings of approximately 442 tons each year.
In 2007, Pinnacle West increased its travel reduction incentives for employees. Current travel reduction incentives for employees include:
- $50 monthly subsidy toward vanpool expense for employees who commute in any local Valley Metro vans. The employee monthly costs are payroll deducted
- A 100 percent subsidy of the monthly accrued bus fares up to $68 to employees who commute by bus
- Employees carpooling do not pay the monthly $46 for parking at company headquarters
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